用于遗传密码扩展的酪氨酰-tRNA合成酶的正交tRNA特异性的结构基础。
Structural basis for orthogonal tRNA specificities of tyrosyl-tRNA synthetases for genetic code expansion.
作者信息
Kobayashi Takatsugu, Nureki Osamu, Ishitani Ryuichiro, Yaremchuk Anna, Tukalo Michael, Cusack Stephen, Sakamoto Kensaku, Yokoyama Shigeyuki
机构信息
Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
出版信息
Nat Struct Biol. 2003 Jun;10(6):425-32. doi: 10.1038/nsb934.
The archaeal/eukaryotic tyrosyl-tRNA synthetase (TyrRS)-tRNA(Tyr) pairs do not cross-react with their bacterial counterparts. This 'orthogonal' condition is essential for using the archaeal pair to expand the bacterial genetic code. In this study, the structure of the Methanococcus jannaschii TyrRS-tRNA(Tyr)-L-tyrosine complex, solved at a resolution of 1.95 A, reveals that this archaeal TyrRS strictly recognizes the C1-G72 base pair, whereas the bacterial TyrRS recognizes the G1-C72 in a different manner using different residues. These diverse tRNA recognition modes form the basis for the orthogonality. The common tRNA(Tyr) identity determinants (the discriminator, A73 and the anticodon residues) are also recognized in manners different from those of the bacterial TyrRS. Based on this finding, we created a mutant TyrRS that aminoacylates the amber suppressor tRNA with C34 65 times more efficiently than does the wild-type enzyme.
古菌/真核生物的酪氨酰 - tRNA合成酶（TyrRS）-tRNA（Tyr）对与其细菌对应物不会发生交叉反应。这种“正交”条件对于利用古菌对来扩展细菌遗传密码至关重要。在本研究中，以1.95 Å的分辨率解析得到的詹氏甲烷球菌TyrRS - tRNA（Tyr）-L - 酪氨酸复合物的结构表明，这种古菌TyrRS严格识别C1 - G72碱基对，而细菌TyrRS使用不同的残基以不同的方式识别G1 - C72。这些不同的tRNA识别模式构成了正交性的基础。常见的tRNA（Tyr）身份决定因素（鉴别子、A73和反密码子残基）的识别方式也与细菌TyrRS不同。基于这一发现，我们构建了一个突变型TyrRS，它对琥珀抑制tRNA进行氨酰化的效率比野生型酶高65倍，C34处被氨酰化。
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